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The Dredge Report | Week of May 30, 2021

Sand Shifter – Allen Harbor Channel, Harwich

Dredging started on June 1st with the Sand Shifter working just outside of the east breakwater in the entrance to Allen Harbor. There are several discharge locations designated by the town of Harwich including Grey Neck Beach and several private residences. Dredging continued throughout the week up until Saturday when dense fog initially postponed operations then wind / seas from the west/southwest restricted dredging operations.

Pre-Dredge for Allen Harbor

The Pre-Dredge survey plan for Allen Harbor. The target volume is 10,913 Cubic Yards.

It’s Not All About Dredging!

As the dredge season goes, the majority of the time is spent on the project location setting up, dredging and then breaking down and moving onto the next project. It is pretty much non-stop except for weather and the infrequent mechanical breakdown’s that occur.

There isn’t much time for routine maintenance, either onboard the dredges or other equipment as well as with the 15,000 feet of pipe that is used throughout the season. We’ve had several sections of pipe damaged this season, some by the strong currents in the Stage Harbor & Aunt Lydia’s Cove areas moving the pipe and ‘bending’ it as well as by a boat that ran over the pipe in shallow waters while the pipe was on the bottom (the propellers cut large ‘gashes’ in the pipe).

A ‘Fusion Machine’ is rented when time becomes available and last week we took the opportunity to repair the pipe in Harding’s Beach and at Cow Yard Lane in Chatham.

Below you’ll find some photos that show the fusion process.

First off, the reason why this process works is that the pipe (High Density Polyethylene (HDPE)) can be cut and heated to ‘melt’. Basically the pipe is cut so you have clean and straight ends, then the two sections (one section of pipe and one ‘flange end’) are placed together, and a large plate is inserted between the two pieces. This plate is heated to 430 degrees F and is kept in place for 8 minutes then removed. Pressure is applied by hydraulic clamps and the two pieces are left to cool and harden for 20 minutes.

The ability to repair pipe is essential to keep the pipe in working condition.

Pipe being loaded onto the Fusion Machine

Dredge Foreman Tanner Dailey directs the lowering of the pipe onto the Fusion Machine


Fusion Machine - cutting

What looks like a ‘meat slicer’, it shaves the pipe creating a clean straight edge on each side of the pipe.

Fusion machine - heating

The fusing process underway, two sections are heated together.